Metallized copolymers of acrylonitrile and vinyl chloride



July 28, 1959- H. J. HOMER m 2,897,098

METALLIZED COPOLYMERS OF ACRYLO NITRILE AND VINYL CHLORIDE Filed 001;. 20, 1954 n w Q q I q Wag w 0 Q w o x IF] I o w V) w Q Q m y INVENTOR HOWARD J. HOMER JOHN R. WHITHCRE 8 K o 0 BY g I ATTORNEYS United States METALLIZED .COPOLYMERS OF ACRYLO- NITRILE AND VINYL CHLORIDE Howard J. Homer and John R. Whitacre, Dayton, can, assignors to The Commonwealth Engineering C om= pany of Ohio, Dayton, 'Ohio, a corporation of Application October 20, 1954, Serial No. 463,376

7 Claims. (Cl. 117-107) This invention relates to metallized synthetic textiles and textile materials in which the metal component is substantially integral with the textile material. More specifically the invention relates to metallized textiles comprised of copolymers of acrylonitrile and vinylchloride in yarn, fabric, tape and similar forms. Specifically thisinvention relates to the provision of metallized synthetic textiles in which the metal is substantially irremovable from the textile material even on severe abrasion, the metal generally being removable from fabrics, for example, only with portions of the material itself.

While metal coatings have hitherto been adhered to glas and the adhesion is good, such metal and glass products contain two distinct phases and the metal does not pass into the body of the glass generally in a manner similar to that, for example, in which water wets fabrics through.

In the product of this invention the metal appears to wet the textile material through and when a strand of the material has been metalized in accordance with the invention is untwisted it is found that the metal exists substantially uniformly throughout the product, coloring it to some extent ordinarily, but lacking the sheen characteristics of metal on glass fiber.

An important object of the present invention is the provision of anti-static coverings which strongly resist wear under. service conditions, for example, in belting, cushions and similar articles of manufacture.

The invention also contemplates the metallizing of fabricated articles articles of synthetic yarns comprised of copolymers of acrylonitrile and vinylchloride, as well as the metallizing of individual yarn strands.

. The process of metallizing is of particular importance in connection with both fabrics and strands due to the fact that no cross bridging of metal between adjacent yarn strands occurs and no brittleness results in the product.

Strands which have been metallized may be taken apart just as are the unmetallized strands and it will be found that the metal when applied in accordance with the precepts of this invention has become a part of the material itself and does not appear to be, even under the electron, microscope, a distinct phase.

The foregoing and other allied objects of the invention are achieved by subjecting the textile material comprised of a copolymer of acrylonitrile and vinylchloride to the action of a thermally decomposable gaseous metal bearing compound.

The textile material is heated and when the same contacts the gaseous compound, the compound decomposes to deposit metal throughout the body of the textile.

2,897,998 Patented July 2 8, 1959 In the usual case such as when nickel is deposited, for example, the white color of the textile becomes a deep gray and this coloration exists throughout the material, for when the same is sectioned through, the cut portion appears grayish also. This latter is in direct contrast to the action occurring when cotton threads are metallized, as the sectioned portion then ordinarily is whitish even though the coloration may extend to some slight portion into the material.

More specifically, in the product of the present invention the textile material is thoroughly impregnated with metal. The metallization in accordance with the precepts of the present invention is not such as to apply a continuous metal coating over the material, that is, it is not a film, but has more the appearance of a textile which has been wetted, the metal apparently permeating the material much as do liquids which wet textiles. However, the metallization is suflicient to change the electrical conductivity of the textile materially and it has been uniformly found that a product which has an infinite resistance per inch of length prior to metallization, will suitably have a conductivity of about two million ohms per inch after metallization. This conductivity is sufficient to prevent the development of static charge when the metallized material is subjected to frictional effects, such as in power transmission belting applications, in coverings for cushions, drapes, and so forth.

The metallic component may be derived from any heat decomposable compound which is decomposable at the temperature to which the textile material may be raised to effect the thermal decomposition;

The thermal decomposition may be effected by passing the material through a dielectric field, but it is preferred, as noted hereinafter in connection with the specific description of the invention, to pass the textile rapidly over a heated surface and then into a chamber containing an atmosphere of the thermally decomposable gas or gases.

The invention will be more fully understood by reference to the following detailed description and accompanying drawings wherein:

Figure 1 is a perspective view diagrammatically illustrating apparatus for the metallizing of substantially continuous lengths of fiber in accordance with this invention;

Figure 2 is a vertical sectional view taken through the apparatus of Figure l on line 2-2 thereof;

Figure 3 is a cross sectional view taken on line 3-3 of Figure 2;

Figure 4 is a view partially in section of a power transmission belt of the V type, rubberized and covered with the metallized textile material of this invention; and

Figure 5 is a View of an automobile seat cover partially in section employing the metallized fabric of this invention.

The textile to be metallized in accordance with this invention, that is, the copolymers of the acrylonitriles and the vinylchlorides are characterized by their substantially infinite electrical resistance; high softening point, in the range of 350-400 F.; a usually white color unless they have been dyed which may be effected with cellulose dyestuiis at the boil; substantially no loss of strength in the wet state; high elastic recovery; a specific gravity slightly greater than water, that is, about 1.2; a shrinking temperature above C. and when exposed to the flame of a match yarns shrivel rapidly; a water absorbency of about 0.5 percent and a high chemical resistance. r

The metallizing process now to be described affects most particularly the shrinking in heat, which is less with the metallized product; the electrical resistance is reduced to about 2 million ohms per inch and effectively hinders accumulation of static by the textile, while the product retains its capacities as a textile material, the flexibility for example being unaffected by the metal.

With most metals the color changes from white to gray or black and the specific gravity increases only very slightly. Shrinkage in boiling water and shrinkage in dry heat, at 125 C., which are low in the unmetallized yarn, are reduced still further in the metallized product. The tensile strength in the wet and dry state is substantially unaffected by the metallization, although when highly stretched during the processing to be described, the tensile strength tends to increase.

Referring now to the drawings, and particularly to Figures 1 and 2, there is indicated generally at three bobbins of yarn on spools 12, the strands of which are drawn together at pulleys 14 before they pass into an insulated heating chamber 15. Heating elements 16 are arranged in the metallic base 17 of the heater. The combined yarns pass into the slot 18 and travel over the smooth interior surface of the heating element at a high speed to be heated to the decomposition temperature of gaseous nickel carbonyl. The heater is suitably insulated with insulating slabs 19 arranged around the heater and suitably secured to it.

The heating element 16 is connected to a source of electric current by leads 20, 22 and the temperature of the heating is preferably controlled by a rheostat 24 actuated by a thermo-couple 26 electrically connected thereto;

The right hand end of Figure 1 of the plating chamber is provided with an inert gas inlet 28 for passing into the slot 18 of, for example, carbon dioxide, which is drawn leftwardly through the chamber to a gas outlet 30 connected to a source of vacuum at a pressure of about 12 pounds per square inch absolute.

The carbon dioxide flowing leftwardly through the heater not only serves to sealthe heater from the gas plating chamber now to be described, but also, due to its flow counter current to the moving yarn strands, tends to prevent any sticking of the material of the yarn should i the same become softened.

The yarn in its passage, while heated, passes into the plating chamber 34- and is subjected to an atmosphere of nickel carbonyl which is at substantially atmospheric pressure. The carbonyl is supplied'thro'ugh an inlet line 36 and is withdrawn from the gas plating chamber through an outlet 38, and accordingly fresh carbonyl plating gas is continuously supplied to the continuously moving heated yarns.

To inhibit the passage of carbonyl into the heater the heater end (Figures 1 and 2) is provided with a passage for water coolant through inlet coolant line 29 and outlet coolant 31 and this cooling together with'the narrow slot and the action of the moving strands prevents metallic deposit in slot 18. The right hand end of chamber 34 is similarly isolated heatwise from heater 40 by inlet and outlet water coolant lines 33, 35.

The yarns 10 are unsupported in their passage of the plating chamber; rightwardly of the plating chamber the yarn passes through another slotted heating element 40, which element is similar to the heater 15 already described and which itself is provided with inlet conduit 42 and outlet conduit 44 for the flow of carbon dioxide seal- 1ng gas.

The yarns then enter another plating chamber 48 prov ded with inlet 50 and outlet '52, for the flow of heated nickel carbonyl plating gas. Chamber 48 "is heat insu- 2 17teg9from heater 40 by inlet and outlet coolant lines Rightwardly of the chamber 48 an unheated chamber 54 is provided which has an inlet 56 and an outlet 58 through which carbon dioxide is passed. This latter chamber 54 serves as a seal to prevent plating gas from moving into the atmosphere. Coolant inlets and outlets for chamber 54 are suitably provided at 41, 43 and at 45, 47.

To control the speed at which the fibers are drawn through the gaseous metal chamber and the associated heating chamber a variable speed motor 60 is supplied and variable speed operations achieved by employing a temperature actuated rheostat 62. The rheostat 62 is connected to heater '15 through thermocouple 63.

Take up rolls, one for each strand passing through pulleys 64, are indicated generally at 65 as supported on stand 66 and the speed of motor 60 which is itself governed by the temperature of heater 15 controls the drawing speed of the strands.

Thus if the heater 15 temperature increases the yarn speed may be automatically increased also to prevent overheating.

The following examples illustrate the procedure for the metallizing of yarns composed of co-polymers of acrylonitriles and vinyl-chlorides:

In connection with the presentation of the specific examples it is to be particularly noted that nickel carbonyl has an optimum decomposition temperature in the range of about 375-400" F. although it does start to decompose very slowly at about 175 F., and this'decomposition continues during the time of heating from 175-400 F.

A large number of other metal carbonyls and hydride'salso become effective and decompose at temperatures in the range of 350400 F., and accordingly 350400 F.v is a preferred temperature range for metal plating.

Further in connection with nickel'carbonyl it is to benoted that the nickel carbonyl is itself a most'desirable compound from an economic point of view as compared to other carbonyls, as nickel carbonyl is relatively cheap and commercially available.

Example I Yarns of a co-polymer'having 40% by weight of acrylonitrile and 60% by weight of vinyl chloride at a denier of 45 were drawn through the apparatus as described hereinbefore and raised to a temperature of about 375 F. in their passage through the heater at a speed of ap-- proximately 50 feet per minute.

The gaseous nickel carbonyl was flowed into the plating chambers at just slightly less than atmospheric pressure, and this pressure was maintained throughout the plating operation in a temperature of 78 F. in thegas flowing into the plating chambers; thegas when it contacted the hot moving filament decomposed thereon and permeated the filament sufiiciently to effectively deposit metal completely throughout the body of the moving, yarns.

The time of heating to raise the yarns to the temperature necessary for decomposition was only about 3 seconds,

the plating chamber being of a length of about 2 /2 feet. Thereafter the gaseous metallized yarns were drawn through the outlet chamber 54, wherein some cooling'of the filament below the softening point thereof took place, and the yarns were then continuously wound up.-

The procedure provides the yarns with an impregnation of nickel metal sufiicient to'lower the electrical resist-ance thereof to a value of about 2 million ohms per inch, whereas the yarns had an electrical resistancein the unmetallized state of substantial infinity.

Where a great quantity of metal deposit is desired the yarns may be repassed through the plating chamber or additional heating chambers may be added to the apparatus. However, for the purpose of producing antistatic yarns which may be woven into anti-static fabrics useful as belt covers, for exam'plathe described process is suflicient and a rapid one.

but not measurably so, probably about 3 million ohms .per inch.

' Example III The conditions of Example I were maintained precisely except for the temperature of the yarn, which was raised to nearly 400 F. in its passage through the heater. The yarn under this condition remained firm and the resultant metallization was substantially the same as that set out hereinbefore. However, if the speed were reduced to lower values, that is, in the range of 1 foot per minute of linear travel, the softening of the material was such as to distort the product at this temperature condition.

The products of Examples I, II and IH when subjected to the flame of a match or a Bunsen burner tend to become brittle but do not support combustion. Metallization thus improves the flame resistance and the heat resistance of the yarns and fabrics.

Similar results are attained with other carbonyls when the same speeds are utilized, preferred exemplary temperatures being as follows:

F. Paco 275-300 cr co 290-315 W co 300-320 Mo(CO) zoo-32s Most suitably the pressures are at substantially atmospheric although lower pressures down to 1 mm. of mercury may be employed.

Referring now to Figure 4 wherein there is shown a V-belt 72 having a cover 74 woven in the metallized yarns produced in accordance with this invention. Such belt coverings are usually rubberized and frequently are impregnated or coated with such as carbon black to increase their electrical conductivity to an extent sutficient to prevent the accumulation of static charge. However, such belt coverings should not be highly conductive for the belts frequently operate in places where, if accidents occur, they could come in contact with live power lines and accordingly high electrical conductivity is not desirable.

When carbon black, graphite and liquid impregnants employing carbon are employed in such beltings they rapidly wear off on the pulleys and much of their efliciency is exhausted within thefirst few hours of running.

The cover 74 produced in accordance with this invention is rubberized impregnated fabric formed of a copolymer of about 40 percent by Weight of acrylonitrile and about 60 percent by weight of vinyl chloride. The rubber enters the interstices of the fabric and it is preferable to employ only a friction which does not coat the covering, as for example, a skim would. Accordingly the metallized fabric of this invention is exposed to the pulleys on which the belt is to ride and provides a sufliciently conductive path between the pulleys to permit the leakage of charge developed during operation. This is an important feature, particularly in applications such as in flour mills, powder mills, and other places where static discharge cannot be tolerated.

The covering 74 need not be rubberized, but may be bonded to itself at the overlap at 76 with any suitable adhesive. It is to be noted that the cover possesses all the requisite characteristics of a V-belt covering, such as ability to flex to small diameters, to resist heat within the limits usually found in such applications, to resist oil due 'to the chemical resistance of the textile itself, and ac cordingly the covering when employed in conjunction With an adhesive, such as an animal glue, is adapted for long service life even under the most strenuous conditions.

Belt applications wherein oil and exposure is a factor should not employ rubbers, but substances such as neoprene may be utilized.

It is further to be noted that the covering may be readily bonded to the carcass 72 f thebelt.

There is illustrated in Figure at 78 an automobile seat cushion having a metallized covering such as that described in connection with Figure 4 woven from a metallized co-polymer such as dynel and which is elfective to prevent the accumulation of static charge so customarily found on the usual automobile seats.

There has been set forth a novel procedure for the production of a new and beneficial product, not believed to be hitherto attained, and the essential feature is the ability of the co-polymers to apparently take up the metal in much the same manner as cotton takes up water. Accordingly the metal is not only adherent, but is substantially integral with the textile.

It will be understood that this invention is susceptible to modification in order to adapt it to dilferent usages and conditions and accordingly, it is desired to comprehend such modifications within this invention as may fall within the scope of the appended claims.

We claim:

1. An anti-static covering for seat cushions, belting, drapes and the like comprising a copolymer in fabric form composed of strands of acrylo-nitrile and vinyl chloride and having a metal impregnant throughout bonded integrally therewith but resistant to passage of substantial amounts of electricity, said metal being deposited throughout the body of said fabric by thermal decomposition of a heat-decomposable gaseous compound of the metal in contact therewith, the resultant metallized fabric having a conductivity of about two million ohms per inch.

2. An anti-static covering for seat cushions, belting, drapes and the like comprising a copolymer in fabric form composed of strands of acrylo-nitrile and vinyl chloride and having a nickel metal impregnant throughout bonded integrally therewith but resistant to passage of substantial amounts of electricity, said metal being deposited throughout the body of said fabric by thermal decomposition of a heat-decomposable gaseous compound of the metal in contact therewith, the resultant metallized fabric having a conductivity of about two million ohms per inch.

3. As an article of manufacture as in claim 1, and wherein said covering seat cushion comprises an acrylonitrile-vinyl chloride copolymer in the form of a twisted yarn impregnated with iron, said iron being substantially integral with said yarn.

4. As an article of manufacture as in claim 1, and wherein said covering seat cushion comprises an acrylonitn'le-vinyl chloride copolymer in yarn form impregnated with tungsten, said tungsten being substantially integral with said yarn.

5. As a textile material for seat cushions as in claim 1, a flexible product of good hand and drape, comprising in combination molybdenum and a copolymer of acrylonitrile and vinyl chloride in textile form in which the molybdenum is distributed substantially uniformly throughout the textile material, said molybdenum being substantially integral with said textile material.

6. As an article of manufacture as in claim 1, and wherein said covering seat cushion comprises an acrylonitrile-vinyl chloride copolymer in yarn form impregnated with chromium, said chromium being substantially integral with said yarn.

7. As an article of manufacture, a yarn composed of acrylonitrile vinyl chloride copolymer in the form of filaments gas plated with metal and twisted into said yarn and wherein the individual filaments of said yarn are impregnated with metal as deposited thereon by said gas plating and providing a substantially uniform dis- 7 1 tribution of metal throughout the yarn, said gas plated metal being selected from the group consisting of the metals tungsten, iron, nickel, chromium and molybdenum, said filaments having an electrical resistance of approximately two million ohms per inch and which retains its original flexibility and effectively prevents accumulation of static electric charges.

References Cited in the file of this patent UNITED STATES PATENTS 2,443,782 Barnard et a1. June 22, 1948 8 Wizon Feb. 27, 1951 Suchy Aug. 28, 1951 Cesswell Jan. 8, 1952 Brennan Nov. 4, 1952 Roseveare Sept. 22, 1953 Buchanan et a1. Mar. 1, 1955 OTHER REFERENCES 10 Gas Plating Oifers Versatility, Steel, vol. 113, No. 16,

Oct. 19, 1953, pp. 120,121, 124. 

1. AN ANTI-STATIC COVERING FOR SEAT CUSHIONS, BELTING DRAPES AND THE LIKE COMPRISING A COPOLYMER IN FABRIC FROM COMPOSED OF STRANDS OF ACRYLO-NITILE AND VINYL CHLORIDE AND HAVING A METAL IMPREGNANT THROUGHOUT CONDED INTEGRALLY THEREWITH BUT RESISTANT TO PASSAGE OF SUBSTANTIAL AMOUNTS OF ELECTRICITY, SAID METAL BEING DEPOSITED THROUGHOUT THE BODY OF SAID FABRIC BY THERMAL DECOMPOSITION OF A HEAT-DECOMPOSABLE GASEOUS COMPOUND OF THE METAL IN CONTACT THEREWITH, THE RESULTANT 